National on-highway diesel prices were up again last week, rising 2.4 cents to a $3.923 average. Prices are now $1.024 more expensive than the same time last year.


The Lower Atlantic region rose the most at 4 cents, topping out at $3.912, according to the weekly report from the Department of Energy. California remained the most expensive at $4.114.

Not all regions showed an increase. The Rocky Mountain region and the West Coast as a whole were down 1.1 cents and 0.7 cents respectively. The Gulf Coast, which rose 2.6 cents, remained the cheapest at $3.882.

Oil futures on Monday dropped as fears over European sovereign debt grew and the U.S. Congress remained in deadlock over raising the debt ceiling. Crude for August delivery fell $1.31 to $95.93 per barrel.

Washington has been embroiled in debate the past few weeks over raising the debt ceiling, which will allow the government to pay its bills. Credit rating agencies Moody's and Standard & Poor's placed U.S. credit on watch for a downgrade last week. Egan-Jones, a less well-known credit rating agency recognized by the Securities and Exchange Commission in 2008, downgraded the U.S. credit rating from triple A to double A plus on Monday.

Congress has until August 2, just two weeks, to reach a deal before the government faces default. Such a default is expected by many to bring catastrophic consequences for the U.S. economy.